Hematopoietic reconstitution using autologous marrow cells is being evaluated as an adjunct to trials of intensive therapy in resistant sarcomas, small cell carcinoma of the lung, and undifferentiated lymphoma. Pharmacologic amplification of peripheral blood levels of autologous stem cells is being studied as a means of accelerating both immunological and myeloid recovery following intensive therapy in man and in a canine model. Studies of the interaction of autologous peripheral blood and marrow stem cell infusions during reconstitution is being conducted in an animal model. Studies in vitro and clinical trials are undertaken to define the optimal platelet support of cancer patients. Extracorporeal hemoperfusion through immunoadsorbent columns, using continuous flow centrifugation in a canine model and in clinical trials, is being studied as a means of inducing regression in tumors resistant to established forms of therapy. Finally, extensive in vivo studies of changes in immune complexes, suppressor cell activity, and various arms of the cellular immune response are being pursued in an attempt to elucidate the mechanism of tumor regression seen following immunoadsorbent therapy.